Curly top disease, is caused by Beet curly top virus (BCTV) and related viruses in the genus Curtovirus, family Geminiviridae. BCTV severely impacts vegetable, dry bean, and sugar beet production throughout large portions of the western United States from e.g., California and Oregon to Texas, Oklahoma, and Nebraska. Transmitted by the beet leafhopper, Circulifer tenellus, the virus infects a broad host range from many plant families causing disease in over 300 species in 44 plant families.
The virus is typically restricted to broad-leafed plants, as no monocotyledonous plants have been identified as hosts for this virus. The most commonly infected hosts include sugar beets (for which the disease was first named), tomatoes, peppers, beans, potatoes, spinach, cucurbits, cabbage, alfalfa, and many ornamentals. The virus also survives in many weeds, such as Russian thistle (tumbleweed) and mustard.
The wide host range of curtoviruses, the abundance of the beet leafhopper, and increasing acreage of uncultivated rangeland where weeds (e.g., tumble weed) are allowed to grow unchecked are making curly top management increasingly difficult.
For over a century management of curly top disease in the western United States has focused on the large-scale application of insecticides to beet leafhopper over-wintering grounds, as well as insecticide application to crops in efforts to reduce populations of the leafhopper vector. Unfortunately, since leafhopper transmission of curtoviruses requires only a brief feeding interval to introduce the virus into a healthy plant, treating e.g., sugarbeet plantings with insecticides does not effectively block virus all virus transmission. Furthermore, insecticide application has potential for unintended negative biological and environmental consequences.
Resistance to curly top has been identified in a select number of crops, but unfortunately, none of these eliminate the ability of the virus to infect, and some resistant crops exhibit non-desirable traits that are difficult to separate through plant breeding.
Therefore, what is needed in the art are effective means to control beet curly top virus. Fortunately, as will be clear from the following disclosure, the present invention provides for these and other needs.